Free Slurpee day at 7-Eleven

Monday’s summer giveaway may just incite a nationwide sugar rush.

On July 11, the convenience store chain 7-Eleven plans to give away 5 million free Slurpees to customers. In the spirit of the date and the store’s name, each free drink will come in a 7.11-oz. cup, and 7-Eleven plans to give out 5 million in the US and Canada.

The 9th annual "7-Eleven Day" marks the chain’s 84th birthday. The first 7-Eleven opened in 1927, when an employee of an ice company near Dallas started selling bread, milk, and eggs on an ice dock. Other Slurpee milestones listed on the chain's website include the coining of the name “Slurpee” in 1967 by a 7-Eleven agency director, the introduction of Slurpee lip balm in 1998, and the invention of an edible Slurpee straw in 2004. Today, there are 8,600 7-Eleven stores in North America and 41,500 around the world.

But not every Slurpee is the same. For starters, American Slurpees are injected with air, but Canadian ones are not. And there are 26 flavors on the market, all of which are carbonated and about half of which are based on popular sodas, such as Fanta and Pepsi. Then there are the flavors based on movies: Alienade, a strawberry-raspberry lemonade inspired by the soon-to-be released "Cowboys and Aliens," and "Blue Lightning Blast," a raspberry-tangerine combo inspired by "Thor," and meant to turn your tongue blue. And then, there’s the flavor based on a video game, Killzone 3. Dubbed KZ3 Battle Fuel, this orange-flavored Slurpee is meant to get you "amped for an all-night gaming session."

And for those who experience sphenopalatine ganglioneuralgia, also known as a brain freeze, 7-Eleven has some advice: Just press your tongue against the roof of your mouth.